Pseudo-Spin, Real-Spin and Spin Polarization of Photo-emitted Electrons

TL;DR

This paper explores the relationship between pseudo spin, real spin, and spin polarization of photo-emitted electrons in topological materials, revealing compound-specific differences and providing spectroscopic predictions for experimental detection.

Contribution

It introduces a detailed analysis of spin textures and their influence on photo-emission spectra in Bi$_2$Se$_3$ and SmB$_6$, highlighting symmetry-based differences.

Findings

Spin orientation of photo-electrons differs between SmB$_6$ and Bi$_2$Se$_3$

Calculated spin polarization spectra are suitable for experimental detection

Differences are due to symmetry properties of photo-emission matrix elements

Abstract

In this work, we discuss the connections between pseudo spin, real spin of electrons in material and spin polarization of photo-emitted electrons out of material. By investigating these three spin textures for Bi$_2$Se$_3$ and SmB$_6$ compounds, we find that the spin orientation of photo-electrons for SmB$_6$ has different correspondence to pseudo spin and real spin compare to Bi$_2$Se$_3$, due to the different symmetry properties of the photo-emission matrix between initial and final states. We calculate the spin polarization and circular dichroism spectra of photo-emitted electrons for both compounds, which can be detected by spin-resolved and circular dichroism angle resolved photo-emission spectroscopy experiment.